Preventative Monitoring and how it can minimize your Solar O&M expenses – Part I

Software solutions for asset management can provide you with the tools to manage your portfolios from top to bottom, while making your projects more profitable. O&M management is the one area that can truly make or break your projects profitability. To manage a profitable project (maximizing energy yield and revenue while minimizing levelized cost of energy (LCOE)), operations must strike a balance between maximizing production and minimizing cost. The fact that most solar farms have only a small number of moving parts means most owner operators assume their solar energy resources require almost no maintenance outside of scheduled preventative maintenance visits and occasional reactionary corrective maintenance. This is why understanding site characteristics can be so important from a monitoring perspective. Unscheduled O&M costs tend to be the most damaging and unpredictable costs associated with a PV project’s budget model.

This feature will discuss the often overlooked areas that can be addressed with the proper tools, knowledge and understanding that any asset manager can master with a bit of training. When you’re looking at the data from your monitoring system it is necessary to ask yourself these questions:

What am I expecting to see from my data?

What does the data actually tell me?

Is it something I need to address?

Part I: Solar Monitoring Best Practices

Keeping maintenance costs on track with accurate and early preventative monitoring (understanding the warning signs before relying on an alarm diagnosis)

String Level Under-Performance

In a perfect world this one should be easy to diagnose on a monitoring platform, but unfortunately in reality many large commercial or utility scale projects don’t include string level monitoring. It’s important to really understand what you need to be looking for. There can be a number of reasons for string underperformance outside of weather and shade related issues (we’ll cover that separately). The most likely reasons being panel related (soiling or physical damage), blown fuses or issues with MC4 connectors. You will have to rely on your field technicians to identify the actual cause during their inspection but what you can do is accurately identify the area of effect. Normalized string current on a combiner is the equivalent of a weighted average based on the number of strings attached to each combiner. You can’t expect your current inputs to be the same on each combiner when they all have varying amounts of panels tied to them. Normalizing this data allows you to identify the outlier in your dataset (A.K.A – the area of the array your technician needs to investigate).

Weather Kit Calibration and Testing

Giving proper care to your weather stations can save you a lot of headache from a monitoring standpoint. If there is one easy way to screw up your expected energy calculations, this is it. Without proper maintenance your pyranometers might be heavily under or over estimating your irradiance and insolation metrics. Ever find yourself searching for answers when your production ratio is consistently hovering at 70%? Or maybe you just assume your plant has somehow gained a market advantage at its current 130% PR. Do yourself a favor and have your technicians complete some irradiance testing on your weather kits. If your tech’s numbers and your monitoring feeds differ by more than 5%, think about replacing or re-calibrating those devices.

Inverter/Combiner Box Cycling

Inverter and combiner cycling might be the first indication that the equipment is having issues or that site voltage is experiencing irregularities. This type of problem is usually re-occurring and self-correcting in terms of the inverters production, but over time if these events happen more frequently, it can become an unnecessary source of lost revenue. For most utility scale inverters, typical cycling will usually initiate a five minute countdown before the inverter starts back up again on its own. This presents not only a problem for the inverter but also for whoever is monitoring this device. Unless you are looking at minute level power AC data, you are likely to miss this event if all you have is a 10 or 15 minute average. It’s very difficult to differentiate between temporary under-performance due to cloud cover and a cycling event in this case. When you see under-performance like this, take the time to compare with the irradiance values on your pyranometer, if they don’t match up, then it’s time to check in on your voltage, current and inverter state data if available.

About Arbox:

While many aspects of under-performance can be spotted early with enough attention to detail, Arbox Hap provides a comprehensive asset management platform to track all the O&M activities in your portfolio. Project monitoring, KPI customization and alarm notification are built into our software solution to help you better manage your assets.

Contact us today to see how HAP® can help you manage your activities efficiently and boost your bottom line.

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